Electrocatalytic detection of streptomycin and related antibiotics at ruthenium dioxide modified graphite--epoxy composite electrodes.
The application of ruthenium dioxide (RuO2) modified electrodes to the electrocatalytic detection of the saccharide-related antibiotics streptomycin, novobiocin and neomycin, at low fixed potentials, was investigated. The RuO2-modified graphite - epoxy composite electrodes give extremely stable and reproducible catalytic oxidation currents for these antibiotics at potentials as low as +0.2 V (versus Ag - AgCl). Rapid quantification at the micromolar level is therefore possible. Standard calibration graphs for streptomycin and neomycin yielded slopes of 4.43 and 0.08 nA microM-1 over the linear ranges of 1.5 x 10(-6) - 2.5 x 10(-4) and 1 x 10(-5) - 2 x 10(-3) M, respectively. Owing to its catalytic oxidation by the RuIII - RuIV couple, rather than the RuIV - RuVI transition (which catalyses the oxidation of streptomycin and neomycin), novobiocin could be detected at a lower (+0.2 V) potential, with a sensitivity of 1.31 nA microM-1. Detection limits of 1.5, 6.0 and 10 microM were obtained for streptomycin, novobiocin and neomycin, respectively. These catalytic surfaces can be renewed (by polishing), with a surface-to-surface reproducibility of 6.5% for the detection of 5 x 10(-5) M streptomycin. The analytical application of RuO2-modified carbon paste electrodes to the analysis of these antibiotics by flow injection was investigated, with a view to liquid chromatographic separation with electrochemical detection applications.
Leech
D
D
Department of Chemistry, New Mexico State University, Las Cruces 88003.
Wang
J
J
Smyth
M R
MR
D002384:Catalysis; D004563:Electrochemistry; D004566:Electrodes; D004852:Epoxy Compounds; D006108:Graphite; D009355:Neomycin / Q000032:analysis*; D009675:Novobiocin / Q000032:analysis*; D012428:Ruthenium; D017975:Ruthenium Compounds; D013307:Streptomycin / Q000032:analysis*
D004852:Epoxy Compounds; D017975:Ruthenium Compounds; C029017:ruthenium dioxide; D009675:Novobiocin; D006108:Graphite; D012428:Ruthenium; D009355:Neomycin; D013307:Streptomycin